‘Crime is a very hard genre to feminise’... Denise Mina
Photograph: Murdo Macleod for the Guardian

‘In the forensic science course I took at university they used photographs of dead bodies. For ballistics they showed us a guy lying on the floor, and his head had burst. With a shotgun, the air in the pellet expands so that if you shoot into the head the skull blows up. It was just mush but there was an eyeball lying there. What made it human, what made it moving, was the detail. And I really wanted to describe these scenes.’

Crime writer Denise Mina is talking about the starting point for her first novel, the award-winning Garnethill (1999), which she wrote when she was supposed to be working on her PhD at Strathclyde University. Mina and her present setting seem a million miles from such gruesome images. This friendly, funny mother-of-two is perched on the edge of a chair in the airy study of her spacious townhouse in the West End of Glasgow. One of her children is rampaging along the wide corridor outside the study door; her partner is baking bread in the kitchen. So far so normal. But those who know Mina’s brilliant but gruelling Garnethill trilogy and the first two in her Paddy Meehan series know that her work is steeped in darkness.

The main character in her trilogy, Maureen O’Donnell, suffers and we suffer with her. The Field of Blood (2005), the first in the Paddy Meehan series, has a harrowing account of the murder of a child by older children. Mina’s books have looked dispassionately at alcoholism, incest, mental illness and many forms of abuse.

Her new novel, The Last Breath, the third in the Meehan series, is set in 1990, when one of those child murderers is to be released from jail. Meehan, by now a successful columnist living in a posh flat, is offered big money to do an interview with him. She isn’t inclined to do so, partly because her attention is elsewhere - a former lover has been murdered, possibly by the IRA. She has inherited his house and, more importantly, the notes for the last feature he was working on. The plotting is clever, the characterisations deep, and Glasgow is well captured. The novel is another brilliant exploration of the themes of family, friendship and justice.

Mina laughs ruefully at mention of her themes. ‘Every time I write a book I despair because I say to myself, “You’ve written the same fucking book again!” Crime is a very hard genre to feminise. If you have a female protagonist she is going to be looking after her mum when she gets older; she is going to be worried about her brother and sister; she will be making a living while bringing up kids.’

For her, justice is a more complex issue related to the requirements of the crime genre: ‘Crime fiction now is big enough not to need tidy resolutions. But an open-ended resolution has to be made to work in another way. The concept of justice goes with achieving a pleasing solution for the reader, one which doesn’t just have the bad guy shot but which answers those questions about what is just. There’s a deep-rooted belief in a just world - and that makes for good mental health - but all the evidence is that the world isn’t just, so people have to shift reality all the time to get a sense of justice. And I think that’s what crime fiction explores in a really deep way.’

Mina came to crime fiction after a contradictory childhood. Born in Scotland in 1966 to an engineer in the oil industry, she lived all across Europe until she was 16, going to boarding school in Perthshire and other schools in London, Paris and Amsterdam. Through friends of her parents in the diplomatic service she frequently attended children’s parties at ambassadors’ houses. At the same time she had a big, extended working-class family back in Glasgow. ‘My upbringing was middle-class but my parents’ families were both working-class so I had this odd combination of working-class background but in a privileged position.’ She was ‘famously naughty’ and rebellious at her various convent schools and left at 16. ‘I smoked a lot and I was fat and quite sulky - that’s a bad mix.’

Eventually she went to university to study law - ‘that’s a real working-class thing - if you go to university you have to do a vocational course’ - but decided she didn’t want to practise. ‘I was 19 and really intense and I got quite disillusioned.’ Then she came up with the idea for Garnethill. ‘I’d read so much right-wing crime fiction where they find the evidence and shoot the bad guy - I thought there must be another approach.’

She always intended it as a trilogy, partly because it was too big a family story to fit into one novel and partly because she liked the triptych form in art history. The completed trilogy - the other novels are Exile (2001) and Resolution (2002) -has received justifiable acclaim, but she’s not tempted to return to her central character. ‘That would be a betrayal, a reunion tour. And, to be honest, they were really dark books and I got really depressed writing them - I was fucking glad they were finished. I dearly miss Maureen and her brothers but I could never be that intense again. I like to think of Maureen having a nice, quiet time in the Highlands, going off for coffee and making bread.’

After a standalone thriller, Sanctum (2003), she pitched the idea of her current series, which will run to five novels. She ‘really got into’ the Paddy Meehan series but took on a number of other projects too, while pregnant with her second child. ‘I wrote a play last year [Ida Tamson] and I’ve been commissioned to write another for the National Theatre of Scotland. And I started writing comics.’

Indeed, she was the first woman writer to do 12 instalments of comic-book series Hellblazer. ‘I said I’d eat my own guts to write for Hellblazer. They said they hoped it wouldn’t come to that. The series is about everything I’m interested in: theology, detective fiction, the gothic. The guy who draws it lives in Argentina so I was climbing over walls when I was heavily pregnant to film the sites I was using.’

She sees the Paddy Meehan series as a biography. ‘Although in this new one it’s not so much about her personality, it’s about the events around her. She’s more stable and static - that’s daring for me. But I wanted to do the series as a biography of a character because I was interested in whether anyone ever changes and why?’

She laughs suddenly.

‘I’ve met my best friend from 20 years ago through Friends Reunited and she said: “You haven’t changed at all.” I thought: “God - all this work I’ve done, all the crap I’ve gone through, all the personality traits I’ve tried to shed and I’m still the same!”’